(5R)-5-[(1R)-2,2-Dichloro-1-methyl­cyclo­prop­yl]-2-methyl­cyclo­hex-2-en-1-one

Brahim Boualy; Mohamed Anoir Harrad; Larbi El Firdoussi; Mustapha Ait Ali; Corrado Rizzoli

doi:10.1107/S1600536811021933

. 2011 Jun 11;67(Pt 7):o1638. doi: 10.1107/S1600536811021933

(5R)-5-[(1R)-2,2-Dichloro-1-methylcyclopropyl]-2-methylcyclohex-2-en-1-one

Brahim Boualy ^a, Mohamed Anoir Harrad ^a, Larbi El Firdoussi ^a, Mustapha Ait Ali ^a, Corrado Rizzoli ^b,^*

PMCID: PMC3152127 PMID: 21837043

Abstract

The title compound, C₁₁H₁₄Cl₂O, was synthesized by the reaction of a dichloromethane solution of (R)-carvone and potassium tert-butanolate in the presence of a catalytic amount of benzyltriethylammonium chloride in chloroform. The cyclohexene ring adopts a half-boat conformation. The cyclopropyl ring is unsymmetrical, the shortest C—C bond being distal to the alkyl-substituted C atom. The crystal packing is stabilized only by van der Waals interactions.

Related literature

For background to and applications of dichlorocyclopropane derivatives, see: Hirota et al. (1996 ▶); Künzer et al. (1996 ▶); Ziyat et al. (2004 ▶); Fedorynski (2003 ▶). For the synthesis and structures of optically active dihalogenocylopropanes reported by our group, see: Ziyat et al. (2002 ▶); Boualy et al. (2009 ▶); Ziyat et al. (2006 ▶). For puckering parameters, see: Cremer & Pople (1975 ▶).

Experimental

Crystal data

C₁₁H₁₄Cl₂O
M _r = 233.12
Monoclinic,
a = 6.5722 (3) Å
b = 8.4802 (4) Å
c = 10.8022 (5) Å
β = 104.435 (4)°
V = 583.04 (5) Å³
Z = 2
Cu Kα radiation
μ = 4.73 mm⁻¹
T = 294 K
0.25 × 0.20 × 0.14 mm

Data collection

Siemens AED diffractometer
Absorption correction: refined from ΔF (DIFABS; Walker & Stuart, 1983 ▶) T _min = 0.327, T _max = 0.519
2295 measured reflections
1576 independent reflections
1554 reflections with I > 2σ(I)
R _int = 0.057
3 standard reflections every 100 reflections intensity decay: 0.3%

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.126
S = 1.09
1576 reflections
130 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.30 e Å⁻³
Absolute structure: Flack (1983 ▶), 394 Friedel pairs
Flack parameter: 0.00 (2)

Data collection: AED (Belletti et al., 1993 ▶); cell refinement: AED; data reduction: AED; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and SCHAKAL97 (Keller, 1997 ▶); software used to prepare material for publication: SHELXL97 and PARST95 (Nardelli, 1995 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811021933/gk2382sup1.cif

e-67-o1638-sup1.cif^{(14.8KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811021933/gk2382Isup2.hkl

e-67-o1638-Isup2.hkl^{(77.7KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811021933/gk2382Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

Financial support from the Universitá degli Studi di Parma is gratefully acknowledged.

supplementary crystallographic information

Comment

Dichlorocyclopropanes play an important role in organic synthesis, due to the widespread occurrence of these structures in biologically active compounds (Hirota et al., 1996; Künzer et al., 1996). These compounds have found wide applications as substrates for the synthesis of many class of compounds such as pyrethroides (Ziyat et al., 2004), benzocyclopropenes or cyclopentadiene derivatives (Fedorynski, 2003), which are not easily obtained using other starting materials. As a part of our ongoing research aimed at the synthesis of optically active dihalogenocylopropanes from terpenes (Ziyat et al., 2002; Ziyat et al., 2004; Boualy et al., 2009; Ziyat et al., 2006), the title compound has been prepared and its crystal structure is reported herein.

In the title compound (Fig. 1), the cyclohexene ring adopts a half-boat conformation [puckering parameters for ring C6/C1/C2/C3/C4/C5: Q = 0.478 (4) Å, θ = 126.7 (4)°, φ = -171.0 (6)°; Cremer & Pople, 1975] with atom C6 displaced by 0.645 (3) Å from the mean plane through the C1–C5 atoms. The cyclopropyl ring (C7–C9) is tilted by 57.64 (19)° with respect to this plane. As already observed in related compounds (Ziyat et al., 2002), the geometry of the cyclopropyl ring is unsymmetrical, the distal bond to the alkyl-substituted C7 carbon atom (C8—C9 = 1.477 (6) Å) being significantly shorter than the vicinal bonds (C7—C8 = 1.518 (6) Å; C7—C9 = 1.500 (4) Å). The crystal packing (Fig. 2) is governed only by van der Waals interactions. The shortest intermolecular halogen···halogen separation is Cl1···Cl2ⁱ = 3.990 (3) Å (symmetry code: (i) 2 - x, -1/2 + y, 1 - z).

Experimental

Potassium tert-butanolate (4.00 g, 19.8 mmol) was added to (R)-carvone (1.47 g, 9.8 mmol) and benzyltriethylammonium chloride (0.02 g, 0.1 mmol) in dichloromethane (60 ml). The mixture was stirred for 10 min, then chloroform (0.8 ml, 9.8 mmol) was added dropwise over a period of 30 min. The mixture was stirred for 8 h at 25°C, and then hydrolyzed by addition of water (20 ml). The organic layer was separated and the aqueous layer was extracted with dichloromethane (3 × 10 ml). The combined organic extracts were dried over Na₂SO₄ and the solvent was removed under reduced pressure. Column chromatography on silica gel (hexane/ethyl acetate, 5:1 v/v) of the residue gave 1.24 g (5.3 mmol, 54% yield) of the title compound as colourless crystals. Slow evaporation of a chloroform solution of the title compound at 25°C afforded crystals suitable for X-ray crystallographic analysis. M.p. 392 K. [α]²⁰_D = +7.72° (c 1, chloroform). ¹H NMR (300 MHz, CDCl₃, δ_p.p.m.): 1.18 (s, 2H), 1.3 (s, 3H), 1.78 (d, J = 0.9 Hz, 3H), 2.1 (m, 1H), 2.3–2.5 (m, 4H), 6.77 (m, 1H). ¹³C NMR (75 MHz, CDCl₃, δ_p.p.m.): 15.6 (CH₃), 16.0 (CH₃), 28.5 (CH₂), 32.5 (CH₂), 40.8 (C^q), 41.4 (CH₂), 41.8 (CH), 65.8 (C^q), 135.5 (═ C^q), 144.5 (═CH), 199 (C═O). MS (70 eV) m/z (%): 233 [M⁺].